Generally, when it is required to clean a space, a person must uncomfortably bend down to wipe a cloth over the space. In order to save such trouble, recently there have been developed various types of cleaning tools, such as mops with a pad-type cleaning cloth. However, such a mop, which is widely used for cleaning, has a problem in that the pad-type cleaning cloth attached to the shank of the mop is small in surface area, so the cloth becomes easily and undersirably dirty, thus the cloth must be frequently removed from the shank of the mop to be washed, therefore causing inconvenience to a user. Further, the mop has another problem in that, when one desires to clean a narrow space or the lower surface of an object, the width of the pad-type cleaning cloth is wider relatively than the space to be cleaned, so a person inconveniently must bend down to clean such a narrow space.
In order to solve such problems, there have been proposed roller-type cleaning tools, which were filed by the inventor of the present invention and are disclosed in Korean U.M. Laid-open publication No. 2000-0002283 and Korean U.M. Registration No. 20-0201758. The above roller-type cleaning tools overcome the aforementioned problems of the mops having the pad-type cleaning cloth. That is, the roller-type cleaning tools may easily clean a narrow space, and are designed to be rotatable so that the contaminated part of a cleaning cloth is easily replaced by a clean part.
FIG. 1 is an exploded perspective view showing the roller-type cleaning tool, which was filed by the inventor of the present invention and is disclosed in Korean U.M. Laid-open publication No. 2000-0002283. As shown in the drawing, the cleaning tool 10 has the shape of a long cylindrical bar 12 with a handle 11. A cloth drive unit 13 is provided at a lower portion of the cleaning tool 10. Two cloth units 14 are removably mounted to the cloth drive unit 13. Each cloth unit 14 includes a cleaning cloth 35 and a cylindrical body 30. The body 30 is provided with an axial hole 31 so that the body 30 is fitted over a rotor 22 of the cloth drive unit 13. A locking recess (not shown) is provided on the inner surface of the body 30, and engages with a locking projection 28 provided on the rotor 22 so as to prevent the cloth unit 14 from being unexpectedly removed from the cloth drive unit 13. The body 30 also has a screw part 38 which comprises a crest 36 and a root 37 so that the cloth 35 is helically wound around and fastened to the body 30. The reference numerals 20 and 29 denote bevel gears, 24 denotes stator and 27 denotes slot.
FIG. 2 is a perspective view showing a screw part included in the roller-type cleaning tool which was invented by the inventor of the present invention and is disclosed in Korean U. M. Registration No. 20-0201758. The cleaning tool is designed such that a cleaning cloth is helically wound around and fastened to a screw part 7 which is provided on the outer surface of a cylindrical body with an axial hole 70. A plurality of first annular ribs 72 are provided along the entire length L of the screw part 7 at regular intervals. Each of the first ribs 72 is provided with a recess 71. Further, a second annular rib 72′ is concentrically provided between two neighboring first ribs 72. That is, the second ribs 72′ are alternately positioned between the first ribs 72. Each second rib 72′ is smaller in diameter than each first rib 72. The second ribs 72′ prevent the cleaning cloth from being deeply inserted into the spaces between the first ribs 72 when the long cloth is helically wound around and fastened to the screw part 7, thus preventing the surface area of the cloth used for cleaning from being undesirably reduced. Since the cleaning tool is provided with the two types of ribs 72 and 72′ each having a recess 71, similar to a screw part having a crest and a root, the cloth is compressed while being rotated to be wound around the screw part 7. Meanwhile, it is difficult to manufacture a metal mold for producing the screw part having the crest and the root. However, the cleaning tool needs not use the screw part having the crest and the root, thus reducing the manufacturing cost and fraction defective thereof
However, such conventional roller-type cleaning tools have a problem that it is difficult to clean a narrow space of a short distance within reach of a user's arm, because the cleaning tools have the shape of a long bar and a large cloth. Thus, when one desires to clean narrow spaces within reach of a user's arm, only the cloth unit removed from the cleaning tool may be used. However, in the case where only the cleaning cloth is used, it is inconvenient to grasp the cloth.